Field of the Invention
The present invention relates to a liquid ejection head that ejects liquid, a recording apparatus including the liquid ejection head and a heat radiation method for the liquid ejection head.
Description of the Related Art
A so-called thermal method is known as a liquid ejection method for a liquid ejection head. In the thermal method, liquid is heated to be boiled, and the force of bubbles generated by the boiling is used to eject the liquid from ejection orifices. In recent years, in order to meet a demand for high-speed image recording, achievement of a thermal liquid ejection head having a large recording width is desired. An example of such a liquid ejection head is disclosed in Japanese Patent No. 4999663.
The liquid ejection head disclosed in Japanese Patent No. 4999663 includes: a plurality of recording element substrates including ejection orifice lines in which a plurality of ejection orifices is linearly arranged; and a support member that supports the plurality of recording element substrates such that the recording element substrates are arranged along an arrangement direction of the ejection orifices. In the liquid ejection head, because the plurality of recording element substrates is arranged along the arrangement direction of the ejection orifices, an ejection orifice line including a large number of the ejection orifices is formed, and the recording width is made larger by the ejection orifice line.
In the liquid ejection head disclosed in Japanese Patent No. 4999663, the plurality of recording element substrates is placed in one or more lines on the support member. Hence, part of heat that is generated in one recording element substrate when liquid is ejected can be transferred to another recording element substrate adjacent to the one recording element substrate through the support member. At this time, the heat in recording element substrates closer to the center of the line is less easily radiated, and hence these recording element substrates tend to come into a high-temperature state. Accordingly, in the liquid ejection head disclosed in Japanese Patent No. 4999663, a temperature difference between the recording element substrates can become larger along with the liquid ejection. If the temperature difference between the recording element substrates is large, a temperature difference between the liquids respectively existing in the recording element substrates is also large. If the temperature difference between the liquids is large, a viscosity difference between the liquids is also large. As a result, it is concerned that variations in the amount of ejected liquid are large, and may have influences on image quality.